Impact of open ocean dissolution of olivine on atmospheric CO2

on atmospheric CO ₂ , surface ocean pH and the biological carbon pump

Judith Hauck,

P K ¨ohler, JF Abrams, C V ¨olker, DA Wolf-Gladrow

20 August 2014, Climate Engineering Conference 2014, Berlin

S ILICATE WEATHERING

Ruddiman 2001

S ILICATE WEATHERING

Increase of alkalinity

CO

Ruddiman 2001

S ILICATE WEATHERING

Fertilizer for diatoms Biological draw-down of CO

CO

Ruddiman 2001

S ILICATE WEATHERING

CO

uptake?

pH?

Ruddiman 2001

MIT ^GCM -RE ^CO M2

Chemistry C / ALK / N / Si / Fe

CO

dust/Fe

Small Phytoplankton C / N / CaCO

/ Chl

Diatoms C / N / Si / Chl

Zooplankton C / N

Detritus C / N / Si / CaCO

Dissolved Organic Material C / N

Hauck et al., 2013

MIT ^GCM -RE ^CO M2

Chemistry C / ALK / N / Si / Fe

CO

dust/Fe

Small Phytoplankton C / N / CaCO

/ Chl

Diatoms C / N / Si / Chl

Zooplankton C / N

Detritus C / N / Si / CaCO

Dissolved Organic Material C / N

olivine

Hauck et al., 2013

M ODEL EXPERIMENTS

O LIVINE ADDITION

1 Pg per year Small

3 Pg per year

Standard Only silicic acid Only alkalinity Ships

10 Pg per year

Large

C ONTRIBUTION OF ALKALINITY VS NUTRIENTS

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

O ce an ic C O 2 up ta ke (P g C yr -1 )

2000 2002 2004 2006 2008 2010

Time (yr)

3 Pg olivine dissolution per year

effect of alkalinity + nutrient

alkalinity effect

nutrient effect

C ONTRIBUTION OF ALKALINITY VS NUTRIENTS

0.0 0.001 0.002 0.003 0.004 0.005 0.006 0.007 0.008

0.0 0.001 0.002 0.003 0.004 0.005 0.006 0.007 0.008

(p H ) (- )

2000 2002 2004 2006 2008 2010

Time (yr)

3 Pg olivine dissolution per year

effect of alkalinity and nutrient

alkalinity effect

nutrient effect

C HANGES IN PRIMARY AND EXPORT PRODUCTION

-3 -2 -1 0 1 2 3

-3 -2 -1 0 1 2 3

C flu xe s (P g C yr

)

2000 2002 2004 2006 2008 2010

Time (yr)

3 Pg olivine dissolution per year

diatom NPP +14%

nano NPP -4%

C HANGES IN PRIMARY AND EXPORT PRODUCTION

-3 -2 -1 0 1 2 3

-3 -2 -1 0 1 2 3

C flu xe s (P g C yr

)

2000 2002 2004 2006 2008 2010

Time (yr)

3 Pg olivine dissolution per year

diatom NPP +14%

NPP +2%

nano NPP -4%

C HANGES IN PRIMARY AND EXPORT PRODUCTION

-3 -2 -1 0 1 2 3

-3 -2 -1 0 1 2 3

C flu xe s (P g C yr

)

2000 2002 2004 2006 2008 2010

Time (yr)

3 Pg olivine dissolution per year

diatom NPP +14%

NPP +2%

nano NPP -4%

Export +1%

CaCO

export -5%

S TANDARD RUN : D IATOM PRIMARY PRODUCTION 30

-30 0 15

-15

gC m

yr

S TANDARD RUN : N ANO PRIMARY PRODUCTION

S CALING FACTORS

-0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0

-0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0

C fl u x e s (P g C y r -1 )

0 1 2 3 4 5 6 7 8 9 10

Olivine dissolution (Pg yr ^-1 ) ocean carbon uptake

NPP

Export production

CaCO ₃ export

D ISTRIBUTION VIA SHIPS

N ORMALIZED SHIP TRACK DENSITY

1

0 0.5 0.75

0.25

S IZE OF PARTICLES TO DISSOLVE IN MIXED LAYER ?

sinking speed: Stokes’ law

dissolution rate based on Hangx & Spiers, 2009

S IZE OF PARTICLES TO DISSOLVE IN MIXED LAYER ?

Ideal scenario

S IZE OF PARTICLES TO DISSOLVE IN MIXED LAYER ?

Ideal scenario Shallower MLD

S IZE OF PARTICLES TO DISSOLVE IN MIXED LAYER ?

Ideal scenario Lower SST

S IZE OF PARTICLES TO DISSOLVE IN MIXED LAYER ?

Ideal scenario Increased grain size

P ARTICLE DISSOLUTION IN REAL OCEAN

0 20 40 60 80 100

R at e of di ssol u ti on ( % )

d = 1 µm

L IMITATIONS AND R ^ISKS

Limitations

Distributing 3 Pg olivine per year: full-time commitment of more than 300 large ships → compensation of approx. 9%

of anthropogenic CO ₂ emissions

Ships of opportunity (using ballast water): maximum potential distribution: 0.9 Pg olivine per year

Need grain sizes of 1 µ m (sinking speed) → grinding

reduces carbon sequestration efficiency from approx. 90 to

60%

L IMITATIONS AND R ^ISKS

Risks

Dissolution of heavy metals possible - toxicity?

Impact on marine species distribution

Potential for extension of anoxic or suboxic regions

Environmental and social problems with mining of olivine

L IMITATIONS AND R ^ISKS

Risks

Dissolution of heavy metals possible - toxicity?

Impact on marine species distribution

Potential for extension of anoxic or suboxic regions Environmental and social problems with mining of olivine Simplifications

Effects of iron-addition, reduction of water transparency not considered

Impact on oxygen not quantified

L IMITATIONS AND R ^ISKS

Risks

Dissolution of heavy metals possible - toxicity?

Impact on marine species distribution

Potential for extension of anoxic or suboxic regions

Environmental and social problems with mining of olivine